Saving Seeds Bulletin No. 1: Beans and Peas
The Fabaceae family is a large family of plants that include the genus’ Pisum (peas), Lens (lentils), and Phaseolus (beans). This family of plants has perfect flowers, and are self-pollinating- because they have both a functioning male and female part that are capable of reproducing at the same time.
The flowers dehisce (shed) their pollen the night before the flowers open. Once opened, the flowers never close back up. Much of the fertilization of Fabaceae occurs when the plants are disturbed by wind or other sources. However, even though the fertilization of perfect flowers usually occurs within the flower, a small amount of cross-pollination can occur. For gardeners wishing to guarantee the purity of seed, species isolation must occur (for isolation instructions, see Saving Seeds Bulletin No. 9). Recommended isolation distance for peas without mechanical isolation is fifty feet, bush beans twenty feet, pole beans 1/2 mile, fava beans 1 mile, and runner beans 1/2 mile. This can vary depending on any physical barriers that may be present, for example rows of corn between varieties.
It is not generally recommended to save seed on the same plants that food is being harvested because the biological function of the plant is to reproduce (form seed), therefore the plant will slow down production once pods are left on to mature. In the case of the Fabaceae family, the space required to grow the plants is often minimal, so growing some for food and some for seed is easy. Twenty plants of each variety is standard for seed saving, however the older the variety-- and therefore the more genetic heterogeneity-- the more plants should be grown to preserve the diversity. However, Fabaceae is an inbreeder, so saving seed from only one plant is possible, because this family does not suffer from inbreeding depression. If the gardener is going to eat from the same plants that seed will be saved, the length of the harvest period should be carefully considered in order to leave enough pods on the plant that will reach full maturity (well past quality eating stage) to provide seed for next year’s planting. If possible, six weeks after the legumes were at quality eating stage is when they are ready. This can be difficult to achieve for beans in the Northwest. Planting before the soil temperatures are high enough may be required. According to the Organic Seed Alliance, color-seeded varieties are the least sensitive to cool conditions. (see www.seedalliance.org) Young plants are more frost tolerant than mature bean plants.
If climate allows, leave pods on the plants to dry. If weather doesn’t permit, remove the whole plant and hang to dry. The least effective option is to remove mature, green pods to dry off of the plant. This method produces less viable seeds, since the seeds can’t pull energy from the plant.
Once the seed pods are crispy dry, remove the seeds by either hand splitting the pods, or by placing them in a pillow case, tying the bag shut, and jogging on the sack. Next, winnow the seeds to remove plant debris.
It is important to make sure that Fabaceae seeds are dry before storage. To test the seeds, place them on a hard concrete surface and hit with a hammer. If the seed shatters, it is dry. Then freeze the dry seeds for five days in an airtight container. Freezing kills weevil larvae that can ruin seeds. Once five days has elapsed, remove container from freezer and allow it to come to room temperature over 24 hours time. Do not remove seeds before this time. Then store seeds in a cool, dry place until ready for use.
